Quantum Sufficit

Just Enough

SARAH EVANS

LINNEA KORINEK

Am Fam Physician. 2004 Dec 1;70(11):2063.

Can you improve your vision while you sleep? According to a report published in The Wall Street Journal, the U.S. Food and Drug Administration has approved contact lenses to be worn during sleep to temporarily correct myopia. The idea is known as orthokeratology; the lenses press on the cornea and temporarily flatten it, thus redirecting light rays closer to the retina. They must be worn every night to afford full benefit. Studies have shown that 93 percent of patients achieve at least 20/32 vision, and 67 percent acquire 20/20 vision. While the long-term effects of nightly cornea pressing are unknown, the lenses are considered to be safe.

Following the destruction of the World Trade Center towers, rescue and recovery workers in New York experienced persistent new-onset or worsening respiratory symptoms after exposure to huge amounts of airborne contaminants. The National Institute for Occupational Safety and Health supported a program of medical assessments of workers and volunteers, and between July 2002 and August 2004, evaluated almost 12,000 persons and analyzed data from a subset of the entire study group. Eligibility for the study was based partially on duration of exposure to the site. Many of the study participants were involved in rescue and recovery efforts on September 11 and through September 14, 2001, the time of greatest exposure. An account in Morbidity and Mortality Weekly Report states that lower respiratory symptoms were reported by 60 percent of the subset group, and upper respiratory symptoms were reported by 74 percent, with most of the study subjects having symptoms that persisted an average of 32 weeks after they stopped working at the site or after the end of May 2002, when site clean-up officially ended. Only 21 percent of the workers and volunteers had sufficient respiratory protection in the early days of the clean-up effort.

A German man who lost his lower jaw nearly 10 years ago to a malignant tumor regained the ability to eat more than soup this year when he was given an engineered jawbone. Physicians began by scanning his jaw and creating a computerized virtual jaw that was then translated into a fine-mesh structure made of titanium. Small cubes of bone mineral from cows, inserted in the structure, were bathed in human growth factor and the patient’s bone marrow, which was rich in stem cells. After incubating inside his latissimus dorsi muscle for seven weeks, the structure was transplanted into his jaw. According to The Lancet, the hope is that the metal can be removed in about a year, and teeth can be implanted into the new bone that is forming.

Teenagers have an increased risk for substance abuse if their friends are sexually active. A study conducted by the National Center on Addiction and Substance Abuse at Columbia University and published in The New York Times reported that teenagers who said that at least one half of their friends were sexually active were 31 times more likely to drink, 5.5 times more likely to smoke, and 22.5 times more likely to try marijuana. The study of 1,000 teenagers interviewed by telephone also found that teenagers who spent more than 25 hours a week with a boyfriend or girlfriend were five times more likely to drink and 4.5 times more likely to use marijuana than a peer who spent less than 10 hours a week with a significant other.

The noise produced by a motorcycle can be as damaging to the sense of hearing as listening to loud music. The University of Florida reported results of a pilot test of 33 motorcycles; approximately one half of the bikes produced sounds higher than 100 dB when they were revved up. This sound intensity is the equivalent of a loud rock concert or a chain saw. The National Institute for Occupational Safety and Health warns that permanent hearing loss can occur with prolonged exposure to any noise measuring more than 85 dB. Inexpensive foam earplugs, found at drug stores, can reduce sound levels by 20 to 25 dB.